This invention relates to a method of reading data out of a data storage medium such as an optical disk. In addition, this invention relates to a recording medium for storing a procedure of the reading method.
In general, an optical disk device is known as a reading device for reading data out of a disk. On reading stored data as read data out of an optical disk medium for storing modulated data as the stored data, the optical disk medium is supplied to the optical disk device. More particularly, the optical disk device reproduce the stored data as the read data to transfer the read data to a host computer. As a result, it is possible to use the optical disk device as a data storage device for a personal computer.
By the way, a read error may occur on reading the stored data out of optical disk medium by the optical disk device. More specifically, the optical disk medium has a plurality of sectors each of which defines an unit of a storage region. Each of the sectors has a DATA-SYNC portion which is for use in determining a synchronism of reading data. When a specific one of the sectors has an extrinsic defect or a microscopic dust, the read error occurs in the specific sector on reading the stored data out of the specific sector.
In order to circumvent such a read error, read retry processing is known as a conventional read retry processing which is disclosed in Japanese Unexamined Patent Publication Tokkai Hei 5-189876 (189876/1993) or Japanese Unexamined Patent Publication Tokkai Hei 6-139718 (139718/1994). It will be assumed that a specific one of read parameters is used on reading the stored data out of the specific sector. When the read error occurs in the specific sector, a first one of read parameters is used as a varied read parameter instead of the specific read parameter in the conventional read retry processing. When the read error again occurs in the specific sector on using the first read parameter, a second one of the read parameters is used as the varied read parameter in the conventional read retry processing. The conventional read retry processing makes the varied parameter be varied until the read error does not occur in the specific sector.
As described above, it is necessary to continue the read retry processing until the read error does not occur in the specific sector. More particularly, it is necessary to change or modify the read parameter in the conventional retry processing until the read error does not occur in the specific sector. Accordingly, it takes a long time duration to finish the retry processing, inasmuch as the retry processing is repeated until the read error does not occur in the specific sector.